Add avgPool2d implementation

include/kernels/pool.cuh

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <cuda_runtime.h>
+#include "layer.hpp"
+
+namespace CUDANet::Kernels {
+
+__global__ void max_pool(
+    const float* __restrict__ d_input,
+    float* __restrict__ d_output,
+    const Shape input_shape,
+    const Shape output_shape,
+    const Shape pool_shape,
+    const Shape stride_shape,
+    const Shape padding_shape
+);
+
+__global__ void avg_pool(
+    const float* __restrict__ d_input,
+    float* __restrict__ d_output,
+    const Shape input_shape,
+    const Shape output_shape,
+    const Shape pool_shape,
+    const Shape stride_shape,
+    const Shape padding_shape
+);
+
+}  // namespace CUDANet::Kernels